Splinting and casting articles for orthopedic purposes such as immobilization of body parts typically are constructed from porous fabrics that are coated or impregnated with plaster of paris or curable resins. Most of the curable resin systems and the plaster of paris systems are cured or rigidified by exposure to water or aqueous catalyst systems.
Once applied to the patient an effective orthopedic article must provide sufficient strength to protect the immobilized body part. It is also desirable that it be light weight, easy to apply, resistant to degradation due to environmental conditions, particularly water, relatively fast and convenient to cure and sufficiently breathable to allow good oxygen transport and transmission of volatile materials from the skin.
When using orthopedic articles systems which are cured by water or water activated catalysts, it is desirable and necessary to allow ready access to the casting system by water in order to obtain both rapid and complete cure. On the other hand, it is desirable that once cured, the orthopedic article dry as rapidly and completely as possible and be relatively insensitive to water, so as to allow bathing and discretionary exposure to water. It is also desirable that the dried orthopedic article provide improved breathability and porosity to minimize the exposure of the skin under the cast to a continuing moist environment.
The present invention provides for the first time a unitary, ready to apply splinting or casting article which combines the advantages of a porous exterior covering layer and yet protects the skin from leakage of the resin impregnated into the casting material.
The present invention provides an improved orthopedic splinting or casting article which cures rapidly and which has an exterior covering layer. The exterior covering layer has a low surface energy and a porosity sufficient to be breathable while not allowing leakage of its contents. The low surface energy exterior is provided by treatment of the exterior layer of the article, with, for example, a suitable chemical such as a fluorochemical or a silicone. The orthopedic article is constructed of a flexible or moldable substrate that is impregnated with a compound that cures the substrate into an inflexible, load-bearing surface. In the context of this application, "a flexible substrate that is impregnated with a curable compound" is equivalent to "a casting material". Preferably, the article is unitary and comprises a water activated resinimpregnated structural member and a porous exterior covering layer. The cure rate of the resin-impregnated structural member can be adjusted to be faster or slower, while providing improved breathability and improved water-repellency to the article.
In general, casting materials currently available which are constructed of resins impregnated into a sheet comprise resins with surface tensions lower than water. The surface tension of the exterior surface of the orthopedic article of this application is significantly lower than water and known resins and therefore the article is water repellent.
It is also an object of the invention to provide a very porous orthopedic splinting or casting article with improved handleability, e.g., which may be handled without protective gloves. The casting resin is enclosed by a low surface energy exterior layer having a porosity that provides excellent containment of the resin before cure. This means that the liquid curable resin does not migrate through the porous exterior covering layer, thereby providing an article with improved storage stability.